Download 2.1 Broken Line Graphs Notes

Chapter 2: Graphical Representations
Math 20-3 Notes
2.1 Broken Line Graphs
Holy Cross Collegiate
Ms. MacLean
2.1 Broken Line Graphs
A broken line graph shows information by plotting values and joining them with line segments. They are
usually used to show change over time, display data, or identify a trend. Businesses use broken line
graphs to help inform them and their clients of patterns.
The title of the graph and the labeling
of the horizontal and vertical axes tell
you about the data being shown.
The independent variable goes on the
horizontal axis and the dependent
variable goes on the vertical axis.
You can use statistics to compare the
number of members that join the gym
over the course of a year.
Statistics: the collection, presentation,
and analysis of numerical data.
- The above graph shows the number of new members at Tough Guy Gym for each month.
- There were30 new members in January. This could be attributed to New Year’s resolutions.
- The month with the lowest number of new members is October.
Broken line graphs can also be used to compare sets of data using a multiple broken line graph. A
multiple broken line graph needs to indicate what each line represents. This can be done by using a
legend in the corner that indicates what each color or pattern represents.
A broken line graph may help you discover a regular pattern in the data. It may show a generally
increasing or decreasing trend, which can allow you to interpolate or extrapolate a value.
Interpolating means to estimate a value between two values shown on the graph. In other words, you
can estimate values on a graph when there are “holes” in the data.
Extrapolating means to predict a value from beyond the given data shown on the graph. In other words,
you may be able to estimate a new value from the data if there is a general trend of increase or
decrease.
Chapter 2: Graphical Representations
Math 20-3 Notes
2.1 Broken Line Graphs
Holy Cross Collegiate
Ms. MacLean
Exemplars
A. Based on the graph below, interpolate the number of factories XYZ Company owned in 1970.
XYZ Company owned 6 factories based on the data from 1960 and 1980.
B. The following table shows the total value of admission fees collected at a festival over a one-hour
period. Draw a broken line graph using the data.
Total sales of admission fees
Time elapsed
Total sales
(minutes)
0
$0
10
$65
20
30
40
$180
$240
$375
50
$405
60
$445
Chapter 2: Graphical Representations
Math 20-3 Notes
2.1 Broken Line Graphs
Holy Cross Collegiate
Ms. MacLean
Examples
1. A music school has been keeping track of the number of people who participate in group sessions
over the course of a year.
Number of Participants in Group Music
Sessions,
by Month
Number of participants
s
44
40
36
32
28
24
20
16
12
8
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
4
m
Month
a) In which month did the most number of people attend group music sessions?
The most participants came to group music sessions in March.
b) In which month did the least number of people attend?
The least number of people participated in August.
c) Is there a trend in the number of people attending the sessions? If so, what might explain the trend?
The class seems more popular in the winter and attendance is low in the summer. People are probably
doing outdoor activities in the warmer weather instead of attending music classes.